Display devices known in the art display information and receive input from a user.
Japanese Unexamined Patent Application Publication No. 2012-123513 (Patent Literature 1) describes an information processing device as one such display device, which is connected to a server in a communicable manner. The information processing device determines an object to which the sightline of the user is directed based on coordinate information indicating the position of the sightline of the user in an image displayed on a screen, and object information including area information indicating an image area including an object. When detecting an object to which the sightline of the user is directed, the information processing device selectively performs processing intended for the detected object. The information processing device further generates target object information indicating the detected object, and transmits the generated target object information to the server.
Japanese Unexamined Patent Application Publication No. 2009-227246 (Patent Literature 2) describes an operation input device for vehicles including a camera, as another example of the above display device. This operation input device for vehicles includes a control circuit that detects the sightline of an operator operating an operational panel from an image captured with the camera. When the detected sightline is in a predetermined sightline state for permitting an operation input, the control circuit switches the operational panel from an operation input prohibited mode to an operation input permitted mode.
The display device known in the art may be a programmable display device, which is connected to a programmable logic controller (hereafter also referred to as a PLC) in a communicable manner. Japanese Unexamined Patent Application Publication No. 2008-112222 (Patent Literature 3) describes an operation display device as an example of the above programmable display device. The operation display device stores a facial image of an operator together with the history of operations performed by the operator.